Therapeutic and diagnostic medical procedures utilize equipment capable of processing signals that are received from a subject or are delivered to a subject. In these procedures, the interface between the subject and the applicable equipment typically includes a sensor. Some sensors, for example, are in the form of electrodes constructed to include a conductor connected electrically to the medical equipment and a conductive medium that is adapted for contact (e.g., with an adhesive) with the subject (e.g., a subject's skin).